The present invention relates to an environmental control chamber and, more particularly, to an environmental control chamber with, for example, a semiconductor exposure device or a coordinates measuring machine by an optical interferometer mounted in its inner space, the environmental control chamber being connected to an air conditioning apparatus.
A conventional environmental control chambers of this type comprises a closed space that is connected to an air conditioning apparatus having an air blower, a cooler, a heater and a temperature controller and controlled so as to maintain temperature, humidity and a degree of air cleanliness (hereinafter referred to as an xe2x80x9cair cleanliness degreexe2x80x9d) within the chamber at their constant values. In the environmental control chamber may be disposed, for example, a semiconductor exposure device (hereinafter referred to as a xe2x80x9cstepperxe2x80x9d).
As shown in FIG. 4, reference numeral 1 denotes an environmental control chamber as a whole with a stepper 2 disposed therein. The stepper 2 is structured in such a way that rays of illuminating light are irradiated from an illumination optical system 3 onto a reticle 4 and that a desired pattern formed on the reticle 4 is illuminated as an image through a projecting lens 5. In a member 6 disposed immediately under the projecting lens 5 are located a wafer 7 and a wafer stage 8 and the wafer 7 with a photoresist layer coated thereon is exposed to rays of projecting light emitted from the projecting lens 5, thereby transcribing the image constituted by the desired pattern formed on the reticle 4.
In the stepper 2, it is required to align the rays of projecting light projected from the projecting lens 5 with the wafer 7 at a high degree of precision in order to allow an accurate exposure of the rays of projecting light to the wafer. At this end, the coordinates of the wafer stage 8 for an alignment of the wafer 7 disposed thereon are measured by means of a end measuring machine 9 by a laser interferometer. The end measuring machine 9 by the laser interferometer is designed to allow a laser head 10 to send laser light out to reflecting mirrors 11, respectively, disposed at a peripheral side portion of an outlet through which the rays of light projected for exposure of the wafer 7 and on the wafer stage 8. The laser light emitted is reflected by the reflecting mirrors 11 and returns to and detected by the end measuring machine 9 by the laser interferometer. The end measuring machine 9 by the laser interferometer then can measure the distance between the reflecting mirrors 11 by detecting the laser light returned thereto by reflection. The alignment of the wafer 7 is then carried out on the basis of this result.
As turnovers of semiconductor elements prepared by transcribing the pattern of the reticle 3 onto the wafer 7 are affected to a great extent with an amount of dust in the air, a high air cleanliness degree is required in the environmental control chamber 1. The stepper 2 is provided with a relay board 12 for controlling an electrical instrument system of each device that acts as a source of heat. Further, the laser head 10 emits heat and also acts as another source of heat. In the chamber 1, it is also required to control the temperature at a predetermined level by controlling a rise in the temperature as well as the cleanliness of air so that the chamber 1 is connected to an air conditioning device 13.
The air conditioning device 13 comprises an air blower 14, a heater 15 and a cooler 16. The air conditioning device 13 is arranged in such a manner that air is discharged from the chamber 1 and air is introduced from the outside into the chamber 1 through an intake opening 17 and an intake duct 18. The air introduced into the air conditioning device 13 is then subjected to adjustment of temperature with the heater 15 or the cooler 16 and sent to the chamber 1 with the air blower 14 through an air outlet 19. The air outlet 19 is provided with a filter (not shown) that can remove dust from the air to be introduced into the chamber 1.
The air conditioning device 13 is arranged in the manner as described hereinabove so as to sustain the temperature within the chamber 1 by controlling the temperature of the air while circulating the air within the chamber 1 in a given course of a path. Further, the air conditioning device 13 can remove dust from the air by means of the filter mounted in the course of the path through which to circulate the air, thereby controlling the air so as to sustain the air cleanliness degree within the chamber 1.
With the arrangement of the environmental control chamber 1, it is further required to not only control its temperature, humidity and air cleanliness degree, but also sustain the air therein in a stable fashion by controlling fluctuations of air without being affected by the outside environment, because the air fluctuations may adversely affect precision of the end measuring machine 9 by the laser interferometer and other optical sensors. More specifically, for the end measuring machine 9 by the laser interferometer, the air fluctuations in the course of the path of the laser light emitted for measurement may cause a variation of a reflective index and such a variation may cause an error of measurement, thereby resulting in a decrease in the precision of alignment of the wafer 7.
In order to avoid this, hitherto, attempts have been made to decrease a variation of temperature and unevenness of temperature by improvements in performance for controlling the temperature of the air conditioning device 13.
However, the stepper 2 to be disposed in the chamber 1 is provided with a variety of heat sources, e.g. different kinds of light sources, actuators, the relay board 12 and other devices and those devices are mounted directly on the main body of the stepper 2. Hence, a space is located around those heat sources therein, where the temperature differs locally. Such a difference of the temperatures cannot completely be removed simply by controlling the temperature of the air circulating within the chamber 1 by the air conditioning device 13.
Therefore, the conventional environmental control chambers suffer from the disadvantages that the fluctuations of air caused to occur in such an space where the temperature varies irregularly are transferred to the path of laser light of the end measuring machine 9 by the laser interferometer or to the wafer stage 8 by circulating the air and that the temperature is transmitted to other places within the chamber 1.
The present invention has been completed with the above matter taken into account and it has the object to provide an environmental control chamber so adapted as to avoid fluctuations of air to be caused to occur on account of a difference of temperatures due to the provision of heat sources in the chamber.
In order to achieve the object as described hereinabove, the environmental control chamber according to the present invention is so adapted as to maintain a space with a main body of a device located therein and with a given kind of fluid filled therein in an optimized environment for operating the main body of the device by circulating the fluid in a predetermined course of a path by an air conditioning device and controlling the temperature and/or humidity and/or air cleanliness degree of the fluid; the chamber being provided with a heat-discharging space disposed on the downstream side of the path from a heat source located in the main body of the device so as to be adiabatic from the space where the main body of the device is disposed; in which the heat-discharging space is constructed so as to gather heat generated from the main body of the device and the heat gathered is discharged to the air conditioning device by the aid of a flow of the fluid circulating through the path.
The environmental control chamber according to the present invention may be constructed in such a manner that an element structuring the heat source of the main body of the device is disposed in the heat-discharging space or that the element structuring the heat source thereof is connected to the heat-discharging space via a heat exchange device.
In the environmental control chamber according to the present invention, there may be employed, as the fluid, air or an inert gas such as nitrogen, neon, argon, krypton, xenon or radon.
Further, for the environmental control chamber according to the present invention, the heat source is a relay board of the semiconductor exposure apparatus and/or a laser head of an end measuring machine by a laser interferometer, when the main body of the device is a semiconductor exposure apparatus.
Furthermore, the environmental control chamber according to the present invention is so adapted as to maintain a space with a main body of a device located therein in an optimized environment for operating the main body of the device, the chamber being provided with a heat-discharging space delimited from the space for locating the main body of the device and structured so as to be heat insulating from the space; and with a cooling device for cooling the heat-discharging space. For the environmental control chamber according to the present invention, the heat-discharging space may be closed from the space with the main body of the device located therein.
In addition, the environmental control chamber according to the present invention may be provided with the heat-discharging space which may be in a shape of a box and which may be made of a heat insulating material.
Other objects, features and advantages of the present invention will become apparent in the course of the following description with reference to the accompanying drawings.